1. GIG
Read the passage and mark your answers on your whiteboard. NOT ON THE PAPER.
Questions 5-6.
Have your writing instruments and calculator ready.

2. 1-D Motion Test Absolute silence.
No leaving the room until you have turned in your test.
Finished? Quietly take your test to the Turn In basket, then silently work on your genius hour project.

3. Relative Motion

4. Why Does it Seem Like the Running Man is not Moving?
Because his velocity is the same as the videographer on the train.
Relative to each other, the runner and the train have a velocity of zero.
To a person watching from a nearby building, they are both moving with the same velocity.

5. What is Relative Motion?
Relative motion is the motion of one object relative to another object.

6. Relative Motion
If you are standing on the ground, the train is moving m/s relative to you while the worker on the train is moving 16.2 m/s relative to you.

7. Relative Motion
If she turns around, her velocity relative to you is the train’s velocity of m/s plus her velocity relative to the train of m/s, which equals 13.8 m/s

8. 2-D Relative Motion
What if someone is climbing the train? His motion relative to the ground is still just a matter of adding vectors.

9. Solving 2-D Relative Motion
If the worker climbs up at 0.20 m/s and the train moves right at 0.70 m/s, what is the worker’s velocity relative to the ground?

10. Solving 2-D Relative Motion
If the worker climbs up at 0.20 m/s and the train moves right at 0.70 m/s, what is the worker’s velocity relative to the ground?
Use the pythagorean theorem to find magnitude
(0.20 m/s)2 + (0.70 m/s)2 = Vtotal2 = 0.73 m/s

11. Solving 2-D Relative Motion
If the worker climbs up at 0.20 m/s and the train moves right at 0.70 m/s, what is the worker’s velocity relative to the ground?
Use trigonometry to find the angle
tanθ = (0.20/0.70)
θ = tan-1(0.20/0.70) = 16°

12. A note about subscripts
Subscripts in relative motion problems usually have two letters indicating:
1. The object in motion
2. The relative object
tg - train’s motion relative to ground
wt - worker’s motion relative to train
wg - worker’s motion relative to ground

13. Homework
None.

14. Closure Answer on your whiteboard:
An airplane moves down the runway at 16.5 m/s. A flight attendant on the airplane is moving toward the tail of the plane at 1.2 m/s. What is the flight attendant’s velocity relative to the ground?